Tube dryers have been provided in the prior art in many configurations such as those illustrated in U.S. Pat. Nos. 3,060,595, 3,199,224, 3,262,217, 3,525,164, 3,199,213, 4,109,394 and 4,139,648. The prior art includes a jet tube dryer especially suited to the drying of flat layers of particulate material manufactured by Martin Processing, Inc. of Martinsville, Va. Dryers constructed in accordance with such prior art have disadvantages in that the free ends of the tubes are unsupported so that the tubes become easily misaligned due to dislodgement so that the pattern of the air being directed by the tubes is distributed thereby, in the case of fabric, causing uneven drying which would result in streaking. It is important therefore, that the tubes remain in alignment at all times so that as the material passes by the array of tubes at least one or more tubes are arranged to be directed against a particular longitudinal portion of the material passing thereby for drying. The proper patterns of air directed against the longitudinally moving material must insure even drying entirely thereacross.
An advantage of tube dryers resides in the fact that the tubes provide ample space for a cross-flow of air for return for being again heated without interferring with the impinging air flow. A particular advantage of tubular dryers constructed in accordance with the invention resides in the fact that the cross-flow is implemented whereas the heated air is held in impinging relation with the material to be dried for a substantially longer period of time.
Should the conveyed material such as cloth or fabric become excessively relaxed or slack, there is a possibility that such can be caught on the tubes and when this occurs the tubes become dislodged due to such snagging with damage to the oven. It is important that the air be applied in regular patterns and retained as long as possible near the fabric to permit the useful heat to be dissipated and utilized in the drying operation.
It is thus seen that an important object of the invention is to prevent streaking which occurs as a result of two things, one, if there is a large flow of air across the oven, past the impinging jets, the tubes permit free area for flow in order to avoid excessive disturbance of the impinging jets and this is facilitated by the structure of assemblies constructed in accordance with the invention. Secondly, the jets themselves must, since each one directs air at the fabric in a given area even distribution of such areas all across the fabric as it goes down the oven and should one of these tubes come out of alignment some areas of the fabric might get subjected to a double drying action and some none at all with streaking occurring as a result.